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g-C3N4 nanosheets functionalized silicon nanowires hybrid photocathode for efficient visible light induced photoelectrochemical water reduction
摘要： We report the fabrication of hybrid Si nanowires @ g-C3N4 nanosheets based photocathode using metal assisted chemical etching and facile liquid exfoliated process. The g-C3N4 nanosheets on Si nanowires form hybrid heterojunction photocathode, which exhibits an enhanced photon induced water reduction activity enabling higher photocurrent density of 22 mA cm?2 with applied bias photocurrent conversion efficiency of 4.3% under visible light irradiation. The onset potential of cathodic photocurrent is positively shifted from 41 to 420 mV vs. RHE with the short circuit current density, Jsc of 0.50 mA cm?2 owing to superior charge transport in hybrid photocathode as compared to pristine Si nanowires for hydrogen evolving reaction at pH～7. The electrochemical impedance spectroscopy measurement elucidates the interface layer of g-C3N4 nanosheets form hybrid heterojunction with Si nanowires that result significant increment in solar water reduction activity owing to low charge transferred resistance with high life time of excited electrons in conduction band. This strategy may open to design a new low cost stable hybrid heterostructure photocathode for solar induced water reduction.
关键词： Solar water reduction,Si nanowires,Photocathode,g-C3N4 nanosheets,Interface
更新于2025-11-21 11:01:37
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A direct one-step synthesis of ultrathin g-C3N4 nanosheets from thiourea for boosting solar photocatalytic H2 evolution
摘要： Two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets, as the promising photocatalyst with fascinating properties, have become a 'rising star' in the field of photocatalysis. Although g-C3N4 nanosheets exfoliated from the bulk g-C3N4 powders are extensively emerged, developing a simple synthetic approach is still full of challenge. To this end, here we report a direct polymerization strategy to fabricate the ultrathin g-C3N4 nanosheets, that is only heating treatment of thiourea in air without addition of any template. The photocatalytic activities of as-prepared samples were evaluated by photoreduction of water to hydrogen (H2) using triethanolamine as sacrificial agent and Pt as co-catalyst under visible-light irradiation (λ > 420 nm). As a result, our few-layered g-C3N4 nanosheets with an average thickness of 3.5 nm exhibit a superior visible-light photocatalytic H2 evolution rate (HER) of 1391 μmol g?1 h?1 and a remarkable apparent quantum efficiency of 6.6% at 420 nm. Eventually, the HER of as-fabricated ultrathin g-C3N4 nanosheets is not only much higher than the dicyandiamide-derived g-C3N4 or melamine-derived g-C3N4, but also greater than the thermal-oxidation etched g-C3N4 nanosheets under the same condition.
关键词： g-C3N4 nanosheets,Template-free polymerization,Solar energy conversion,2D materials,Photocatalysis,One-step synthesis
更新于2025-11-14 17:03:37
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Novel PtPd alloy nanoparticle-decorated g-C3N4 nanosheets with enhanced photocatalytic activity for H2 evolution under visible light irradiation
摘要： PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g–1 h–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g–1 h–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.
关键词： H2 evolution,PtPd alloy nanoparticles,Photocatalysis,g-C3N4 nanosheets
更新于2025-11-14 17:03:37
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Soluble g-C3N4 nanosheets: facile synthesis and application in photocatalytic hydrogen evolution
摘要： The high dispersibility and solubility are highly required for the potential applications and development of well-known g-C3N4 material. In this study, a facile hydrothermal treatment and the following vacuum freezing-drying process was developed to synthesize the g-C3N4 nanosheets (ca. 5 nm) with excellent dispersibility and solubility in aqueous solutions. It was found that the melem structures with many hydrophilic groups (-NH2, -OH and -C=O) were formed on the g-C3N4 nanosheet surface, resulting in the formation of soluble g-C3N4 (SCN) nanosheets. Moreover, the SCN nanosheets can be worked as the effective modifier to greatly increase the H2-production performance of conventional g-C3N4 photocatalyst (the resultant sample was referred to SCN/g-C3N4). Photocatalytic results revealed that the SCN/g-C3N4 sample exhibited a remarkably higher H2-production performance than the pure g-C3N4 by a factor of ca. 2. The improved H2-production rate of SCN/g-C3N4 photocatalysts could be primarily ascribed to the introduction of hydrophilic groups, which not only remarkably enhances the dispersibility and hydrophilicity of SCN/g-C3N4, but also work as the interfacial active sites to accelerate the H+-reduction reaction and the rapid formation of H2. The present soluble g-C3N4 nanosheets provide potential various applications in environmental protection and energy conversion fields.
关键词： photocatalysis,H2-evolution,solubility,g-C3N4 nanosheets,dispersibility
更新于2025-09-19 17:15:36
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Boosting the photocatalytic ability of g-C3N4 for hydrogen production by Ti3C2 MXene quantum dots
摘要： The big challenging issues in photocatalytic H2 evolution are efficient separation of the photoinduced carriers, the stability of the catalyst, enhancing quantum efficiency and requiring photoinduced electrons enrich on photocatalysts’ surface. Herein, Ti3C2 MXene quantum dots (QDs) possess the activity of Pt as co-catalyst in promotion the photocatalytic H2 evolution to form heterostructure with g-C3N4 nanosheets (NSs) (denoted as g-C3N4@Ti3C2 QDs). The photocatalytic H2 evolution rate of g-C3N4@Ti3C2 QDs composite with an optimized Ti3C2 QDs loading amounts (100 mL) is nearly 26, 3 and 10 times higher than pristine g-C3N4 NSs, Pt/g-C3N4, Ti3C2 MXene sheet/g-C3N4, respectively. The Ti3C2 QDs increase the specific surface area of g-C3N4 and boost the density of active site. Besides, metallic Ti3C2 QDs possess excellent electronic conductivity, causing the improvement of carrier transfer efficiency.
关键词： Ti3C2 MXene quantum dots,Photocatalytic H2 production,g-C3N4 nanosheets,co-catalysts
更新于2025-09-19 17:13:59
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Ultrathin WO3 nanosheets modified by g-C3N4 for highly efficient acetone vapor detection
摘要： In this work, ultrathin WO3 nanosheets were prepared by self-assembly approach and their phase and morphology were regulated by changing the heat treatment temperature. Then, g-C3N4 modified WO3 nanosheets sensitive material was fabricated via a facile liquid ultrasonic mixing method. The microstructure, morphology, chemical composition, oxidation state and surface area of WO3 nanosheets and g-C3N4/WO3 nanocomposite were comparatively studied by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). Sensing performances of WO3 nanosheets and g-C3N4/WO3 composite with different g-C3N4 loading amount were investigated with acetone as a target gas. Compared to WO3 nanosheets, the g-C3N4/WO3 gas sensor exhibits good response, excellent selectivity, transient response and trace detection ability to acetone vapor. Effects of g-C3N4 content on gas sensitivity were also investigated. The response (Ra/Rg) of the gas sensor based on 1 wt% g-C3N4/WO3 was 35 toward 100 ppm acetone at 340 °C, which was about 300% higher than the response value of pure WO3 sensor. The sensor also showed a fast response/recovery speed (9 s/3.8 s) and a wide linear detection range (from 0.5 ppm to 500 ppm). These unique sensing properties were attributed to the synergistic effects including the contribution of WO3 ultrathin nanosheets, suitable crystal phase and porous surface, and the sensitization of g-C3N4, which increases the specific surface area and regulates the electrical properties. This work will contribute to the development of new acetone sensors and expand the application of g-C3N4 composite materials.
关键词： g-C3N4 nanosheets,acetone detection,nanocomposites,WO3 nanosheets
更新于2025-09-10 09:29:36
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Fabrication of novel 1D/2D V2O5/g-C3N4 composites as Z-scheme photocatalysts for CR degradation and Cr (VI) reduction under sunlight irradiation
摘要： Photocatalytic materials for environmental remediation of organic pollutants and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, 1D/2D V2O5 nanorods/g-C3N4 nanosheets (VONRs/CNNs) composites were prepared by a facile impregnation method and employed in the degradation of a Congo red (CR) and reduction of Cr (VI) under sunlight irradiation. The as-prepared samples were studied by several characterization techniques including XRD, SEM, TEM, EDS, XPS, FTIR, UV-vis DRS and PL. Results revealed that the interface interaction between VONRs and CNNs was recognized via V2O5 nanorods loading on the surface of g-C3N4 nanosheets, improving the separation and transfer of photogenerated electron-hole pairs and restraining the recombination rate of charge carriers. As a result, the photocatalytic activity of the composites was enhanced in comparison with pure CNNs and VONRs. The photocatalytic efficiency of optimal composite (4-VONRs/CNNs) for the removal of CR (Cr (VI)) was about 9.33 (4.22) and 73.52 (19.2) times higher than that of pure CNNs and VONRs, respectively. Meanwhile, the 4-VONRs/CNNs exhibited good photocatalytic stability in recycling experiments. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electron-hole pairs at the VONRs/CNNs interface imparted through the direct Z-scheme charge carrier migration mechanism. Moreover, the energy band structure and the quenching effects of different scavengers demonstrated that the electrons of CNNs and holes of VONRs with higher oxidizability and reducibility are the real participants in photocatalytic reactions.
关键词： g-C3N4 nanosheets,Z-scheme mechanism,Composites,Photocatalytic activity,V2O5 nanorods,1D/2D heterojunction
更新于2025-09-10 09:29:36
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Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C3N4 nanosheets
摘要： Exfoliation of bulk graphitic carbon nitride (g-C3N4) into two-dimensional (2D) nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g-C3N4 nanosheets (CN) have larger specific surface areas and more reaction sites. In addition, poly-o-phenylenediamine (PoPD) can improve the electrical conductivity and photocatalytic activity of semiconductor materials. Here, the novel efficient composite PoPD/AgCl/g-C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach. The obtained photocatalysts have larger specific surface areas and could achieve better visible-light response. However, silver chloride (AgCl) is susceptible to agglomeration and photocorrosion. The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density, which is three times that of CN. Obviously enhanced photocatalytic activities of PoPD/AgCl/g-C3N4 are revealed through the photodegradation of tetracycline. The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly. Furthermore, ?O2? and h+ are the main active species, which are confirmed through a trapping experiment and ESR spin-trap technique. Therefore, the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst, in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles. This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.
关键词： AgCl,Visible light irradiation,Poly-o-phenylenediamine,g-C3N4 nanosheets,Photocatalytic
更新于2025-09-09 09:28:46
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Design of graphitic carbon nitride supported Ag–Cu2O composites with hierarchical structures for enhanced photocatalytic properties
摘要： A novel ternary photocatalytic nanocomposite, Ag–Cu2O/C3N4, has been successfully synthesized via a facile two-step reduction procedure at room temperature, wherein Ag nanoparticles are directly growing on the surface of Cu2O supported by C3N4 nanosheets. The resulting ternary Ag–Cu2O/C3N4 photocatalyst exhibits enhanced photocatalytic activity towards methyl orange (MO) degradation compared with its conterparts (Cu2O, spherical Ag–Cu2O and Cu2O/C3N4), demonstrating a removal rate of MO up to 95.7% within 30 min. The enhanced photocatalytic activity can be ascribed to the following factors: 1) the surface plasmon resonance effect of Ag nanoparticles broadening the visible light response of Cu2O; 2) the introduction of C3N4 functioning not only as a fast electron delivery but also a fine stabilizer to prevent the Ag–Cu2O composite from agglomeration. Mechanism studies reveal that MO is cracked into smaller fragments and the h+ is the main reactive species participating in the photocatalytic process. Moreover, the Ag–Cu2O/C3N4 photocatalyst also shows high photodegradation ability for another two representative azo dyes, acid orange II and congo red. This study demonstrates the potential of Ag–Cu2O/C3N4 in the degradation of azo dyes and also provides a guide to design of Cu2O-based ternary photocatalysts for further wastewater remediation.
关键词： Wastewater remediation,Cuprous oxide,Photocatalysis,C3N4 nanosheets,Fragments,Mechanism
更新于2025-09-09 09:28:46
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Surface defect and rational design of TiO2?x nanobelts/ g-C3N4 nanosheets/ CdS quantum dots?hierarchical structure for enhanced visible-light-driven photocatalysis
摘要： TiO2-x/g-C3N4/CdS ternary heterojunctions are fabricated through thermal polymerization-chemical bath deposition combined with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions are formed successfully and CdS quantum dots (QDs) and TiO2 are anchored on surface of g-C3N4 nanosheets simultaneously. The visible-light-driven photocatalytic degradation ratio of Bisphenol A and hydrogen production rate are up to 95% and ~254.8 mmol h-1, respectively, which are several times higher than that of pristine TiO2. The excellent visible-light-driven photocatalytic activity can be ascribed to the synergistic effect of TiO2-x, g-C3N4 and CdS QDs which extend the photoresponse to visible light region and favor the spatial separation of photogenerated charge carriers.
关键词： Photocatalysis,Ti3+ self-doping,g-C3N4 nanosheets,CdS quantum dots,TiO2 nanobelts
更新于2025-09-04 15:30:14